CD44 and infection: Moreover, while infection of CEM-SS cells with the D64V IN mutant resulted, as expected, in minimal viral replication (Fig. 1C) and did not reduce cell viability (Fig. 1B), IN− HIV-1 was capable of almost WT levels of replication in C8166 cells (Fig. 1E), resulting in indistinguishable cytopathic effects (Fig. 1D).